I've said this before, but I think what they've done with Star Tours is the general foundation of how they can keep certain rides "fresh" for repeat guests. That is, have multiple "branch" points in the film, each with a variety of options that is randomly selected for each ride.
And it's quite possible to do, though it will take some work. First and foremost, they'll need to switch from film to digital projection. They'll need to sync up appropriate ride movements and musical score to make the transitions seamless. And they'll have to rework the ride control systems to account for the various options rather than a set script.
But it can be done, and once done, it should be far simpler to add to the available options as it was to put the system in in the first place.